Thomas Schmugge

2006 Robert E. Horton Medal Winner

New Mexico State University, Las Cruces

Thomas Schmugge was awarded the Robert E. Horton Medal at the AGU Fall Meeting honors ceremony, which was held on 13 December 2006 in San Francisco, Calif. The medal recognizes outstanding contributions to hydrology.


For the past 30 years, Thomas Schmugge has been a truly peerless intellectual leader in improving both the theory and the application of microwave and infrared radiative transfer for the remote sensing of the land surface, especially soil moisture, surface temperature, and emissivity. Without exaggeration, he has been a trailblazer and is now unquestionably one of the few world experts on remote sensing in hydrology.

He already made his mark in the early 1970s in the remote sensing of soil moisture, snow, and sea ice. In a seminal paper, he was the first to recognize how soil texture affects microwave emission. He then succeeded in developing a theoretical framework explaining how the bonding between water and colloids affects the soil’s dielectric properties. With this he pioneered a model to predict the variation of the dielectric properties of soils in terms of soil moisture; this model is in wide use as the standard method today.

Subsequently, he initiated leading-edge studies to put the relation between the diurnal range of surface temperature and soil moisture on a more quantitative basis; this led to the successful HCMM [Heat Capacity Mapping Mission] satellite experiment in 1978. His work with the thermal IR data from the HAPEX [Hydrologic-Atmospheric Pilot Experiment] experiments in 1986 and 1992 demonstrated how the spectral variation of surface emissivity for both bare and vegetated surfaces can be determined remotely. This work led to his selection as a team member on the U.S./Japan science team for the multispectral ASTER [Advanced Spaceborne Thermal Emission and Reflection Radiometer] instrument for NASA’s Earth Observing System satellite Terra, launched in 1999. Most recently, ASTER data have been used to map the surface emissivity of large arid areas, and these maps are being implemented with great success in climate models to improve the accuracy of the predicted soil moisture, surface temperature, and surface fluxes of latent and sensible energy.

Tom Schmugge has been a tireless catalyst and pathfinder in a number of largescale field experiments applying these techniques to map surface soil moisture. These include HAPEX-Mobilhy in 1986 in southwestern France, FIFE in 1987 in Kansas, Monsoon 90 in Arizona, the Washita 92 experiment in Oklahoma, and the HAPEX-Sahel experiment in 1992 in West Africa. Moreover, in several of them he led the analyses of the microwave radiometer data. His work proved that microwave sensors can determine the soil water content of the 0 to 5 centimeter layer through vegetative canopies up to and including a mature corn crop, with natural surface roughness having only a small effect; it also showed how soil evaporation and soil hydraulic properties can be estimated with such repetitive microwave observations. Schmugge’s approaches are increasingly being implemented by others in this country and abroad to map soil moisture globally, and his findings are already having wide ramifications, generating new data sources from space for use in crop production, atmospheric circulation studies, and runoff forecasts.

The Robert E. Horton Medal is awarded for “outstanding contributions to the geophysical aspects of hydrology.” Schmugge’s accomplishments perfectly embody this ideal. His research has dealt with soil moisture and radiation, the main drivers of the Earth’s energy and water budgets. Moreover, his leadership in remote sensing within AGU and in promoting hydrologic-atmospheric experimentation has been of critical relevance to our science. I cannot think of anyone more deserving of the Horton Medal than Thomas Schmugge.

—WILFRIED H. BRUTSAERT, Cornell University, Ithaca, N.Y.


Thank you, Wilf, for your kind and generous introduction. This is a great honor for me, and I also look upon it as recognition that remote sensing can make a contribution to hydrological problems.

As you noted in your acceptance of the Robert E. Horton Medal a few years ago, you had the good fortune of being in the right place at the right time. This is also true in my case and played a large part in my being here today. I was trained as a solid state physicist across the bay at the University of California, Berkeley, and in the late 1960s when I was looking for a position, none was to be found in that field. So I decided to explore the use of my microwave background in the new field of remote sensing and applied to NASA for a U.S. National Academy of Sciences postdoctoral position. It turns out that Bill Nordberg, a leader in NASA’s Earth observation program at the Goddard Space Flight Center (Greenbelt, Md.), was looking for someone to explore the use of microwave radiometers for land remote sensing. This was just before NASA was to launch its first microwave radiometers on the Nimbus 5 satellite. Our initial studies indicated that both soil moisture and snow had interesting microwave signatures. The soil moisture work was more appealing to me. After more than 30 years of work on the use of microwave radiometers for soil moisture sensing, I am heartened by the prospective launch of the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission next September. I am discouraged, however, by the fact that NASA did not approve its prospective soil moisture mission, Hydros, after several years of studies.

I would like to thank the many colleagues I have worked with over the years in the Hydrological Sciences Branch at NASA Goddard Space Flight Center and the U.S. Department of Agriculture/Agricultural Research Service Hydrology Laboratory, Beltsville, Md., without whose support and collaboration I would not be here today. In particular I would like to mention Tom Wilheit, my office mate early on at Goddard, who taught me microwave radiometry, and Tom Jackson at the Hydrology lab, who showed me the importance of soil moisture to hydrology.

In closing, I want to express my gratitude to AGU for bringing us together and providing a forum for the discussion of geophysical results and to the members of the Horton Medal Committee and the others who supported my nomination.

—THOMAS SCHMUGGE, New Mexico State University, Las Cruces